U.S. Air Force Office of Special Investigations Consisting of more than 2900 federal agents and support personnel, the Air Force Office of Special Investigations has been the Air Force's major investigative service since Aug. 1, 1948. The agency reports to the Inspector General, Office of the Secretary of the Air Force. OSI provides professional investigative services to commanders of all Air Force activities. Its primary responsibilities are criminal investigations and counterintelligence services.